Reversible cage bar and mounting for hammer mills



p 9, 1969 R. M. WILLIAMS 3,465,973

REVERSIBLE CAGE BAR AND MOUNTING FOR HAMMER MILLS 2 Sheets-Sheet 1 Filed June 30, 1967 FlG.l.

w I I A X l I I r I! FIG.2.

INVENTOR ROBERT M. WILLIAMS ATTORNEYS Sept. 9, 1969 R. M. WILLIAMS 3,465,973

REVERSIBLE CAGE BAR AND MOUNTING FOR HAMMER MILLS Filed June $50, 1967 2 Sheets-Sheet 2 a? 39 26 was;

INVENTOR ROBERT M. WILLIAMS ATTORNEYS United States Patent 3,465,973 REVERSIBLE CAGE BAR AND MOUNTING FOR HAMMER MILLS Robert M. Williams, Ladue, Mo., assignor to Williams Patent Crusher & Pulven'zer Co., Inc., St. Louis, Mo., a corporation of Missouri Filed June 30, 1967, Ser. No. 650,489 Int. Cl. B02c 17/02 US. Cl. 241-86 Claims ABSTRACT OF THE DISCLOSURE A hammer mill apparatus in which the cage bars, mounted by wedge means including a protective keeper means therefor, are formed in a manner that allows reversal thereof on the mounting seats in the mill housing so that extended life is possible and efl'icient operation of the mill can be prolonged before cage bars have to be replaced. I

This invention relates to improvements in hammer mills and particularly is concerned with providing reversible cage bars for such mills.

The problem in hammer mills is that trash, dirt, and foreign matter become so firmly jammed into the openings and crevices that it is an extremely difficult job to remove worn cage bars for replacement. Heretofore, cage bars for hammer mills have been discarded when wear thereon destroyed the desired running clearance in the hammer circle. As the cage bars wear and the hammer circle space increases the crushing and grinding effect of the mill rapidly decreases, either in longer time for reducing the material to a condition where it will pass through the grate bars or in failure to reduce the material to the desired fineness condition.

It is, therefore, an important object of the present invention to provide improved cage bars for hammer mills and to mount the cage bars for easy removability.

It is also an important object of the present invention to provide cage bars having a configuration that will readily allow for reversing the position of the bars so that longer life at substantially normal efi'iciency can be obtained therefrom.

It is also an object of the present invention to provide a hammer mill with improved mounting provisions for reversible cage bars.

Other objects and attendant advantages will be hereinafter disclosed in connection with a preferred embodiment of the present invention, particular attention being directed to the several views in the accompanying drawings, wherein:

FIG. 1 is a fragmentary sectional elevational view of a hammer mill embodying the improved reversible cage bars of this invention;

FIG. 2 is a fragmentary transverse sectional view of the cage bar assembly, the view being taken at line 2-2 in FIG. 1;

FIG. 3 is a greatly enlarged perspective view of a part of the mill showing the end mounting of the cage bars;

FIG. 4 is a fragmentary sectional view of the cage bar securing means shown in FIG. 3; and

FIG. 5 is an enlarged cross section of a typical cage bar to show its symmetrical form for reversibility.

In FIGS. 1 and 2 the hammer mill has a base frame portion 11 formed with a bottom opening 12 for the discharge of the crushed material. The frame 11 carries suitable bearings 13 to support the shaft 14 on which the plurality of rotor discs 15 are assembled. The discs 15 carry a plurality of pivoted hammer elements 16 arranged in opposed pairs for purpose of balance. The rotor assembly is confined between opposite end walls 17 in which continuous ring or semi-ring steps 18 (one being shown in FIG. 3) are provided to support the ends 19 of the several cage bars 20. The steps 18 are sufficiently long to seat a group of cage bars in side by side relation.

The upper portion 21 of the mill casing carries breaker plates 22 adjacent the hammers 16, and above these plates are the side walls 23 of the material feed chute 24.

Each cage bar 20 is formed with through openings 25 spaced along its length, and the bar is substantially rectangular in cross section as can be seen in FIG. 5. However, the ends 19 of each such bar 20 are formed with arcuate surfaces 26 on the opposite sides. The arcuate surfaces 26 are determined by an arc whose center is at the center of the rotor shaft 14 and whose radial length reaches to or is measured out to the back side of the bar or that side of the bar remote from the hammers 16. Each surface 26 has the same arcuate configuration so that when one side facing the hammers 16 becomes worn, the bar may be removed and turned over to present an unused side to the hammers 16 so that the hammer clearance space can be again brought into the desired condi tion.

As may be seen in FIGS. 3 and 4, the cage bars 20 are set by the ends 19 on the steps 18 in walls 17. Each bar is provided with a wedge element 27 having an edge surface 28 curved to match the curved surface 26 on the bar, and the opposite edge surface 29 is tapered to provide an adjustable draw-up action when 'abutted on the tapered edge 30 of the arcuate cage ring member or abutment means 31. In addition, the wedge elements are curved to match the curvature of the member 31. Each abutment means 31 may be an elongated circular member which is shaped to match the circular arrangement of the assembled cage bars on the adjacent step 18, and such means 31 is formed with a plurality of bolt receiving apertures 32 which match'apertures 33 in the end wall 17. A series of liner elements 34 are placed over the abutment means 31 such that their flanges 35 drop over the means 31 and the long leg 36 engages the wedge elements 27 as a keeper. Bolts 37 are passed through the liners 34, the apertures 32 and the end wall 17 to the outside where nuts 38 are threaded up to draw the liners up tight against the wedge elements 27 and cause the tapered surfaces 29 and 30 to secure the cage bar ends 19 on the step 18. The bolt heads are recessed in the liner elements 34 to avoid damage thereto during mill operation.

The assembly of the cage bars 20 in the manner shown has the advantage that the liner elements 34, being short pieces as shown, but which can be a single circularly shaped element, makes it easy to dismantle the assembled cage bars. In this connection, it must be realized that the material fed into the hammer mill is pounded and thrown around with great force so that the cage bars are sprung out of shape and distorted, and the liner elements are pounded and disfigured to such an extent that the nuts 38 loosen and become tell-tale indicators to signal tightening is required. The liner also serves to protect the abutment means 31 which is normally welded in its initial assembly to the wall 17. Without the liner in position the abutment means 31 would be pounded out of shape and rendered useless to cooperate with a. fresh set of cage bars. Furthermore, the liner means is provided with the log legs 36 which protect the wedge elements 27 in a similar manner. Eventually, however, the pounding of the material in the mill chamber forces the liner legs 36 to drive the wedge elements 27 deeper into the space between the abutment member 31 and the adjacent end portion of the cage bars. This action, thereby, further tightens the cage assembly and prevents movement that might otherwise destroy the cage ring seats 18.. r

A still further advantage for the hammer mill assembly in the area of the cage bars is that when the wedge elements 27 are removed there is sufiicient space in which to maneuver the cage bars 20 so that distortion, warping and misshaping of the bars can be accommodated during the process of the removal of the bars along the direction of the abutment means 31. The bars can not be angled upwardly between the walls 17 but must be moved sideways along the seat steps 18 in order to achieve removal.

It is now apparent that the cage bar assembly achieves all of the objects desired, and provides a simple way of mounting the bars for easy removal and reversal so that the useful life of the bars can be extended to advantage. It is the aim herein to include all variations of the mounting assembly for reversible cage bars within the spirit and scope of the appended claims.

What is claimed is:

1. A hammer mill comprising a casing having a material discharge opening and opposed pairs of end and side walls adjacent such opening, one of said pair of opposed walls being formed with elongated seats, a plurality of cage 'bars located in working position over said discharge opening with the ends thereof on said seats, said cage bar endshaving opposite side surfaces, each shaped to conform with said seats to allow positioning the cage bars selectively in one of two positions, wedge means engaged between said one pair of walls and said cage bar ends to retain the cage bars in working position, and protective keeper means engaged with and substantially covering said Wedge means against direct impact by material in the hammer mill.

2. In a hammer mill the combination including a mill casing structure having a material discharge defined by at least two spaced opposed walls, each said wall having a circularly shaped elongated seat therein, a plurality of substantially identical cage bars located in assembled positions over said material discharge with the end portions thereof supported by said elongated seats, abutment means carried on each of said Walls in spaced relation to said seat therein, each said abutment means having a tapered edge directed toward the adjacent seat, holding elements for the ends of each cage bar, each element having a first edge shaped to conform to the cage bar end portion it engages and having an opposite tapered edge substantially matching the tapered edge of said abutment means, and liner means secured to said walls over said abutment means and holding elements to force said matching tapered edges on said holding elements and abutment means into wedging engagement.

3. The hammer mill combination set forth in claim 2 wherein the end portions of each cage bar are curved to match said seats, said curved endportions fitting said seats in at least two different positions of each of said cage bars.

4. The hammer mill combination set forth in claim 2 wherein each liner element has a flange portion engaged over said abutment means and a keeper portion engaged over said adjacent holding element.

5. The hammer mill combination set forth in claim 2 wherein said abutment means have circularly curved and tapered edges facing said seats, the end portions of said cage bars slide between said seats and abutment means selectively on assembly and disassembly, each cage bar end portion having at least two dilTerent surfaces circularly shaped to substantially match the circular shape of said seats and said holding elements and liner means being removable to allow selective seating of said cage bars on said seats in at least two different positions.

References Cited UNITED STATES PATENTS 1,322,833 7/1917 Shelton 24l-86 1,470,177 10/1923 McNaughton 241-285 X 2,233,728 10/1938 Bell 241-86 X FOREIGN PATENTS 560,727 7/ 1958 Canada.

ROBERT C. RIORDON, Primary Examiner M. G. RASKIN, Assistant Examiner 

